Process for producing 1.8-hydroxynaphthoic acid



Patented Apr, 5, 1927.

UNITED STATES PATENT OFFICE.

RICHARD EERZ AND FRITZ SCHULTE, OF FRANKFURT-ON-THE-MAILT, GERMANY, AS- SIGNORS '10 GBASSELLI DYESTUFF CORPORATION, OF NEW YORK, N. 'Y., A COR- PORA'IION OF DELAWARE.

PBOCESSIZOR PRODUCING LS-HYDROXYNAPHT HOIC ACID.

No Drawing. Application filed July 12, 1926, Serial No. 122,029.'and in Germany-November 29, 1924. y

We have found a new-process for producing 1.8-hydroxynaphthoic acid, which consists in treating S-cyannaphthalene-l-sulfonic acid of the formula:

. NO 80H with acid sa onifying a ents and in subject 1 ing the pro ucts thus tained to the action of caustic alkalies at elevated temperatures.

The chemical reaction, which takes place,-

runs probably as follows:

(1) S-cyannaphthalene-l-sulfonic acid is. saponified, whereby ammonia is split off and l-sulfonaphthalene-S-carboxylic acid is formed. If the saponification is carried out with concentrated acids, then instead of the s free acid its inner anhydride is obtained.

The acid and its inner anhydride are new compounds.

As an intermediate product, 8-naphthamide-l-sulfonic acid can be isolated, a substance, which also can be obtained by allowing an alkaline sa onifying agent to react on S-cyannaphtha ene-l-sulfonic acid, as

30 described in our copending application,

The following formulas may illustrate the probable course of the reactions:

Probable intermediate product; NC 30:11 H|NOC BOIH S-cyannaphthalene- 8-nahtham1del-a ultonic acid 1v 01110 add HOOC 3 1H l-sulionaphthalene- Inner anhydride of the I S-carboxylic acid l-sultonaphthalene- S-carboxyllc acid ,Hooc on La-hydroxymphtholo acid v The starting material for the reactions,

S-cyannaphthalene-1-sulfonic acid, is easily obtainable in the usual manner by converting 8-aminonaphthalene-1-su1fonic acid into its diazocompound and treating "the latter.

with cuprous cyanid according to the Sandmeyer'reaction. It forms a diflicultly soluble Sodiumsalt, which may be isolated fromits solutions by adding common salt to it, or by equivalent means. The free S-cyannaphthalene-l-sulfonic acid may be obtained by converting the sodium salt into the dilficultly soluble lead salt and setting the acid free in the usual manner for instance by precipitating the lead with the corresponding amount of sulfuric acid or hydrogen sulfide. 8-cyannaphthalene-l-sulfonic acid is very easily soluble in water and shows a strong acid reaction.

The following examples will further illustrate our new process and-the products obtained by it. lVe wish it however to be understood that we are not limited to the particular conditions nor to the specific products mentioned therein. The parts are by weight and the temperatures in centigrade degrees.

Ewample .10 parts of the sodium salt of 8-cyannaphthalene-l-sulfonic acid are dissolved at ordinary temperature in a fiveto sixfold quantity of concentrated sulfuric acid. Then ice is added, until a sulfuric acid of about p. c. strength is formed, and the temperature of the mixture is increased to about After a short time the whole mass solidifies to a pulp of crystals, namely the inner anhydride of l-sulionaphthalene- 8-carhoxylic acid. It crystallizes from benzene in the form of small table s, melting at 151152'.' When warmed with water, it is easily saponified to Lsulfonaphthalene-S- carboxylic acid. This acid may be produced directly in the form of its ammonium salt by warming S-cyannaphthalene-l-sulionic acid with dilute mineral acids, e. g. dilute hydrochloric acid, until-it is totally saponified, and by evaporating the mass to dryness. In order to produce the free acid, one may convert the alkaline salts into the lead salt and set the acid free in the usual manner e. g. by precipitating the lead with the correspondin amount of sulfuric acid or hydrogen sul de.

Example 2.40 artsv of caustic potash are melted with a cut, 8 parts of water. Then 10 parts of the inner anhydride of 1-sulfonaphthalene-8-carboxylic acid, described in the foregoing example, or the corresponding uantity of an alkaline salt of l-sulfonapht alene-8-carboxylic acid are introduced and the temperature of .thefusion is slowly increased to 190-230 and the mass is kept at this temperature for sometime. When the reaction is finished, the fusion mags is diluted and acidified with a mineral aci The 1.8-hydroxynapthoic acid thus formed separates in an almost pure state with an excellent yield. It crystallizes from dilute fonaphthalene-S-carboXylic acid are introduced. Then. methyl alcohol is slowly distilled off, until the temperature reaches 130- 150". At this temperature heating is continued for some hours under reflux.

lVhen the reaction is finished, the mass is diluted and acidified with a mineral acid. The 1.8-hydroxynaphthoic acid, thus se arated, is identical with the acid, descii ed .in example 2.

Example /;.--In an autoclave 10 parts of the inner anhydride of l-sult'onaphthalene- 8-carboxylic acid are introduced at about 80 in about 30 parts of caustic soda solution of 50 B6. Then the mars is heated for 4-6 hours at 230250, correspondinp to a pressure of 12-15 atmospheres. A'tcr cooling down, the formed sodium salt of 1.8-hydroxynaphthoic acid is to a large extent separated in crystalline form.

In order to isolate free 1.8-hydroxynapl1- t-hoic acid, the fusion mass is diluted with water and acidified with a mineral acid.

We claim:

1. A new process for roducing- 1.8-hydroxynaphthoic acid whic comprises treating 8-cyannaphthalene-1-sulfonic acid of the formula:

with an acid saponifyinghgent, treating the product thus obtained w1th a caustic alkali I at an elevated temperature and isolating the formed 1.8-hydroxynaphthoic acid by ac1d1- fying the fusion mass.

2. A new process for producing 1.8-hydroxynaphthoic acid which comprises treating S-cyannaphthalene-l-sulfonic acid of the formula:

NC son! with an acid saponifyin agent, and treating the product. thus-obtamed with a caustic alkali at an elevated temperature.

ing 8-cyannaphthalene-I-sulfonic acid of the formula:

N0 BOaH alcohol, as crystals meltingf at 169 and is identical in all its properties with the acid, described by'Eckstrand (loc. cit), J

Example 8.-80 parts of caustic potash and parts of methyl alcohol are heated for some time at 80-100; at this temperature 20 parts of the inner anhydride of 1-eu1-' with an acid saponifying agent, and treating the product thus obtained with a caustic alkali at an elevated temperature and under alkaline solution at an elevated temperature 30 elevated pressure.

4. A new process for oducing 1.8-hydroxynaphthoic acid which comprises treating 8-cyannaphthalene-l-sulfonic acid o the formula y ing B-cyannaphthalene-l-sulfonie acid of the formula:

v NC

with an a acid saponifymg ing the product thus obtain with a caustic a nt and trcatand under elevated pressure.

6. In the process for producing l.8'-hydroxynaphthoic acid the manufacture of 1-sulfonaphthalene-8-carboxylic acid .in the form of its inner anhydride which com rises saponifying 8 cyannaphthalene 1 -.su fonic acid with a concentrated mineral acid and isolating it, substantially as described.

7. As a new product the inner anhydride of l-sulfona hthalene- 8 carboxylic acid, having proba ly the formula: v V

mung when dry a crystalline powder, melt- :m" e! about 151-152 and being substanna-lly identical with the product obtainable by saponifying .8-cyannaphthalene-lrsuL- fonic acid with a concentrated mineral acid.

tures. I

RICHARD 'HERZ. FRITZ In testimony whereoflwe ailix our sigma- 

